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Kathryn Stack, Mars Rover

May 29, 2014

By Julia Munemo

It’s 2 o’clock in the morning, and Kathryn Stack ’08 groggily fastens the leash to her dog’s collar and heads out into the Pasadena darkness for a walk. When she gets home, she eats breakfast and packs her lunch. She’s thinking about tomorrow, when this whole process will start at 3 a.m. And the day after, when it will start at 4.

Stack, who is finishing her Ph.D. at Caltech this year, spent three months in 2012 living on Mars time. She’s part of the team running the NASA’s Curiosity Mars rover, and for the first three months after it landed, the whole team lived on Mars time. The Mars day is 40 minutes longer than the Earth day, and those 40-minute increments add up. “It starts out okay,” Stack says, “but every few weeks you’re on a complete 12 hour shift with Earth time.”

Stack at the Rio Tinto, Spain, a famous Mars analog site.

Stack came to Williams thinking she wanted to be an astrophysicist. But after a “life changing” tutorial in her sophomore year with geology professor Ronadh Cox, she decided to double major in geosciences and astronomy. “I realized not only how awesome our own solar system was,” Stack says, “but how much about the Earth I didn’t know.” So she took as many geology courses as she could during junior and senior year, and wrote a thesis about giant garnets in the Adirondack Mountains.

In graduate school, Stack wanted to take her knowledge of Earth’s geology to the next level and study the geology of other planets in our solar system. She went to CalTech and spent several years conducting research and creating geological maps based on orbital images of the surface of Mars.

That experience came in handy when the Curiosity team was assembling. “It’s been known for a while that Mars is composed mostly of volcanic rock,” Stack says. “But over the last decade, we have come to understand that Mars has a sedimentary rock record as well.” Her geological maps supported this theory, suggesting there was a diversity of sedimentary as well as volcanic rocks on the planet. She jumped at the chance to explore one of these ancient sedimentary environments with the rover.

For Curiosity’s first few months on Mars, Stack was on the tactical side of operations. She used her geological maps to plan the rover’s route every day and to determine the best spots for it to stop and investigate. “I picked a number of locations near the landing site that I thought would be the most exciting for the rover to explore,” she says. The rover has a suite of instruments—to take pictures, sample and analyze rock, run chemistry experiments, and even drill into the rocks—and Stack helped to plan which tools it would use at each location.

Curiosity’s main goal was to figure out if any parts of Mars had once been habitable. At Yellowknife Bay—one of the spots Stack helped to choose—the NASA team found evidence for an ancient lake and energy sources capable of sustaining life. “This was a place where life could have once existed,” Stack says. Major goal of the mission: accomplished.

Pretty soon Stack was put on the strategic side of the operation. She is now helping to plan not only what the rover will do today or tomorrow, but what it will be doing in five months, or next year.

Stack will continue to work on the Curiosity rover at Jet Propulsion Laboratory, which runs the mission, after receiving her Ph.D. this month.

And although she is relieved not to live on Mars time anymore—research has shown that three months is the most scientists can bear living an almost 25-hour day—she admits that “it was exciting to sleep when the rover slept and work when it was awake.”